Armature for foundation. Calculation of reinforcement for the slab foundation

The reinforcement technology helps to achieve the optimum strength of the building in modern construction. The ways of its implementation are diverse and the choice of the concrete depends on a number of parameters of the fortified object. The armature was most widely used as an element of the foundation - it is thanks to metal rods that a high-strength building component called reinforced concrete is being formed. At the same time, the integration of rods into a concrete base must be strictly calculated, otherwise all efforts to create a reliable platform will be in vain.

Parameters for calculating the valve

Calculation of the volume and parameters of the metal "skeleton" is impossible without knowledge of the required properties relative to the building itself. Based on its characteristics, the reinforcement for the foundation is selected . The calculation is based on several indicators that determine the technical and operational quality of the structure.

The list of basic values includes the following parameters:

• Mass of used rods;
• The length of each element;
• Total weight of the frame;
• Diameter and ribbing;
• Number of rods.

It would seem that the use of the maximum possible amount of reinforcement will achieve the highest technical and operational qualities of the foundation of the building. But this is not so, since an incorrect distribution of loads on the foundation can lead to the opposite effect, weakening the structure.

Calculation for a slab foundation

One of the popular types of foundation is the slab. In this case ribbed rods with a diameter of at least 1 cm are used. The choice of thickness depends on the planned mass of the house and the characteristics of the soil. For example, if a wooden structure is being erected, the calculation of the reinforcement for the slab foundation may imply a minimum permissible thickness. In the case of a stone or brick house, this figure is an average of 1.5 cm. Based on these data, the optimum volume of reinforcing material is selected.

Step Reinforcement Grid

The number of rods, as well as their size, must be calculated by the grid step. So, if the reinforcement is planned on a basement of 6x6 m, the gap will be 20 cm. That is, you need to install 31 pins along and across. Accordingly, the calculation of the amount of reinforcement for the foundation in this case shows the need to use 62 rods. But this is not all - since the plate forms two belts, the primary result is multiplied by two - in total, 124 units are obtained. The total length of the material, provided that one rod has a length of 6 m, will be 744 m.

It also requires a connecting armature. It is calculated individually and based on the width of the belt - these are connecting rods a few decimetre in length. In the case of the foundation described, the total length of the auxiliary reinforcement will be about 100 m.

Calculation for a strip foundation

When constructing a tape base for a house, also an armature with a diameter of 10-14 mm is used. But there is one difference, which determines the specificity of the consumption of rods in such foundations. The fact is that the concrete structure of the belt type is more resistant to bending, therefore the thickness will initially be understated if compared with the slab analogue.

For longitudinal reinforcement, the A3 rods are used. Their function is assigned to receive a direct load on the foundation, which determines the need to use rods with a ribbed surface. Less heavy loads fall on the vertical and transverse elements, so they can be smooth - brand A1. Typically, the calculation of reinforcing bars for the basement foundation involves the installation of four rods in the longitudinal direction - two for each belt. If the reliability requirements are increased due to instability of the soil or the characteristics of the building itself, it is possible to increase the number of rods.

Calculation for a columnar foundation

This type of foundation involves the use of reinforcing rods with the smallest thickness - the diameter is distributed in 1-1.2 cm. The main load is taken by the ribbed vertical rods A3, while the elements of the horizontal direction (0.6 cm thick) perform only the function of the bundle .

As an illustration of the strengthening, you can take a column 2 m long and 40 cm in diameter. Four elements of 1.2 cm in diameter are required, between which a step of 20 cm is kept. They are fastened with smooth bars with a diameter of 6 mm. Relative to the length calculation of columnar foundations can be represented as follows: four vertical bars of 2 m in total will be 8 m.

Reinforcement diagrams

The shape of the metal frame in the concrete base depends on the chosen reinforcement scheme. The latter, in turn, will determine the effectiveness of the configuration used - in each case it can be different.

The main rule in choosing a scheme for forming a structure from metal rods is the bias toward the right forms. The installation of reinforcing elements in the form of a rectangle or square, as practice shows, provides the highest reliability of the building. However, other solutions for the construction of the reinforcing cage are not excluded, if the project of the house itself deviates from the standards.

The layout of the rods in the concrete structure should take into account additional reinforcement, which, however, is not so necessary, if a base plate is being built . Calculation of reinforcement reinforcement is usually used in ribbon reinforced concrete tabs, when corners and joints are formed.

Fastening of armature

Even the correct calculation of the reinforcement will not ensure the reliability and durability of the foundation if an unsuccessful method of fixing the rods is selected. Usually, welding is used to connect metal structures and parts, but in the case of reinforcement it is advisable to stay on a wire fastener - the structure of the material will retain its original qualities, securely reinforcing the concrete.

For this, a binding wire and a special hook are used, which makes it possible to create knots. The optimum strength of the frame is possible only if the connecting sections of the convergence of the rods are evenly connected - the exceptions touch the corner sections, which require reinforcement. In addition, reinforced reinforcement for the foundation, the calculation of which takes into account the "problem" places of joints and turns, will protect the structure from physical impacts.

On average, about 25 cm of knitting wire is used for each joint. Increase the reliability of the junction connection by double strapping, then use a crochet hook.

Errors in reinforcement

The best way to insure against improper selection and installation of fittings is to follow the design documentation. Ignoring the established parameters of construction can be associated with the desire to save, the lack of the necessary material, etc. Each of these cases creates a risk to the safety of the constructed facility. Also it is not recommended to forget about technological rules, on which the reinforcement for the foundation is selected. Calculation of this will optimize further laying, but the main contribution to the success of the project will make the primary quality of the material.

In addition, in the organization and the reinforcement itself, the following errors must be prevented:

• Application of non-conforming to the characteristics of the reinforcement. Smooth rods can not replace analogues with a ribbed surface, as one category of material - another.
• Unprepared metal surface. The presence of grease, corrosion and dirt is unacceptable, since it reduces the adhesive qualities of the material.
• Errors in the calculation of gaps, in accordance with which the reinforcement for the foundation is laid. The calculation of the step from one rod to the other should not be less than 2 cm - this is unreasonable in terms of structural reliability and proportional distribution of loads.
• The connection of the reinforcement in the stretch points of the concrete base. When there is a shortage of reinforcement length, a connection using the lining method is used. Although there are cases when such a device is allowed, it is desirable to avoid unnecessary attachment points.

Features of the calculation of fiberglass reinforcement

Advantages of the composite analog of metal rods determined its popularity. With respect to diameter and weight, the calculation of fiberglass reinforcement for the foundation is somewhat different. First, the innovative material is many times lighter - so, the mass of a 100-meter rebar of fiberglass is 8 kg. Secondly, the composite increases the strength properties of concrete, which makes it possible to reduce the thickness of reinforcement elements. For example, if metal bars with a diameter of 1 cm are declared in the project, then it can be limited to 0.8-centimeter diameter.